We’d all like to help the police to do their job well. They, in turn, would like to have a massive database with DNA profiles from everyone who has been arrested, but not convicted of a crime.

We worry that this is intrusive, but some of us are willing to make concessions, on our principles, and the invasion into our privacy, in the name of preventing crimes. To do this, we’d like to know the evidence on whether this database is helpful, to help us make an informed decision.

Luckily the Home Office have now published a consultation paper on the subject. They defend their database by arguing that innocent people who have been arrested are as likely to commit crimes in the future as guilty people. “This”, they say, “is obviously a controversial assertion”. That’s not true: it’s a simple matter of fact, and you could easily assemble some good quality evidence to see if it’s true or not.

The Home Office have assembled some evidence. It is not good quality. In fact, this study from the Jill Dando Institute, attached to their consultation paper as an appendix, is possibly the most unclear and badly presented piece of research I have ever seen in a professional environment. Or I am having a bad day. Join me in my struggle to understand their work.